It would appear that all persons who were translated before the resurrection of Christ—Enoch and his city, Melchizedek and his city, Elijah, Moses, Alma the Younger, Nephi, and so forth—were resurrected at the time of Christ’s resurrection (see D&C 133:54-55; see also Mormon Doctrine, pp 807-8). Persons who were translated after the time of Christ’s resurrection will minister in their terrestrial state until the Second Advent.
At that time they will be changed in the twinkling of an eye, transformed instantaneously from their mortal (still subject to death) terrestrial condition to a resurrected fully immortal condition.